Interlocking device

ABSTRACT

The specification discloses several embodiments of an interlocking device. The specification discloses a preferred embodiment of an interlocking device having an inner bar slideable within the confines of an outer bar. The outer bar has a first end and a second end. When the inner bar slides towards the second end of the outer bar, a plug, which is attached to the inner bar, is adapted to abut a plug barrier thereby preventing the inner bar from sliding towards the second end.  
     The outer bar of the interlocking device further defines an interlocking member passage and an interlocking member stop. The interlocking device further has an interlocking member attached to the inner bar. When the inner bar slides towards the first end of the outer bar, at least a portion of the interlocking member moves transverse to the sliding axis of the inner bar and into the interlocking member passage. The interlocking locking member further abuts the interlocking member stop, thereby stopping the inner bar from sliding towards the first end of the outer bar. The interlocking device preferably has a cam attached to the outer bar and adjacent to the interlocking member stop. The cam may be actuated to release the interlocking member from the interlocking member stop thereby allowing the inner bar to slide through the confines of the outer bar.

CROSS REFERENCE TO RELATED APPLICATIONS

[0001] This application is a continuation of U.S. patent application Ser. No. 10/198,671, filed Jul. 15, 2002. This application is hereby expressly incorporated by reference in its entirety.

FIELD OF INVENTION

[0002] The present invention relates to locks and fasteners. More particularly, the present invention relates to locks that mechanically interlock an inner member from sliding within the confines of an outer member.

BACKGROUND

[0003] Inner-Outer Member Combination

[0004] Various devices presently utilize inner members that are slidable within the confines of outer members (also referred to as “inner-outer member combination”). An inner-outer member combination allows a user to adjust a device's dimension. For example, some tow bars used for towing vehicles have legs that utilize the inner-outer member combination so that they can easily be stored when not in use. Camera tripods also utilize the inner-outer member combination so that they can be stored in a non-bulky manner.

[0005] Other devices that utilize the inner-outer member combination include: cleaning poles that allow users to extend the poles to reach a desired height and construction devices that extend to a certain height to transport and allow a person to work on an elevated area, such as billboards. The inner and outer members of these devices may have the same shape, but vary in diameter—that is, telescopic.

[0006] Locking Mechanism for Telescoping Legs

[0007] Telescoping legs are used in cleaning or agricultural tools (as disclosed in U.S. Pat. No. 5,154,449), legs of common camera tripods (as disclosed in U.S. Pat. Nos. 4,029,279 and 4,761,092), and musical instrument support (as disclosed in U.S. Pat. No. 4,430,017). All of these telescoping legs have a locking mechanism that stops the inner bar from sliding within the confines of the outer bar.

[0008] U.S. Pat. No. 5,154,449 discloses a lock for telescoping legs. The lock has a cylindrical clamp, a movable block, and an eccentric shield. The cylindrical clamp is actuated by pivoting the eccentric shield, which causes the shield to pinch the clamp to secure the outer tube and to press the movable block against the outer tube. See also U.S. Pat. No. 4,761,092.

[0009] U.S. Pat. No. 4,029,279 discloses another lock for telescoping tubular legs. The lock has a camming lever that engages an inner channel section through a window formed in the outer channel section, thereby locking the inner and outer members. See also U.S. Pat. No. 4,430,017.

[0010] One problem with the locks described above is that they are friction-based locks. Friction-based locks rely on friction to prevent an inner member from sliding within the confines of an outer member. However, friction may be overcome by a strong force. Thus, friction-based locks may only be appropriate for limited applications, such as when telescoping legs are used to support lightweight objects or when telescoping legs are not subjected to strong forces. Friction-based locks are also disclosed in U.S. Pat. Nos. 4,029,279, 4,761,092, and 4,430,017.

[0011] Tow Bars

[0012] Tow bars are devices used for enabling a carrier to tow another carrier. Tow bars are commonly used for enabling a recreational vehicle (an “RV”) to tow a car. Tow bars typically have a pair of legs attached to a leg coupler. The leg coupler attaches to a hitch or a ball mount of the towing vehicle. The other end of the tow bar legs attaches to the vehicle being towed.

[0013] A sample tow bar is disclosed in U.S. Pat. No. 5,382,042 ('042 reference), entitled “Towing Device Support.” The tow bar of the '042 reference has a cylindrical inner member that moves in two directions within a cylindrical outer member. In one embodiment, the cylindrical outer member has a latch attached to one end of the cylindrical outer member. The latch has a handle on one end and a stopping potion and a tooth on another end. The tooth is adapted to abut a dimple on the inner bar. The dimple is substantially a triangular shaped indentation on the inner bar. The tooth of the latch is adapted to go inside the indentation and abut the bottom of the dimple's triangle thereby preventing the inner bar from sliding toward the bottom triangle side. However, the inner member can still move in the opposite direction because the tooth can disengage from the dimple by sliding toward the crest of the dimple's triangle, as there is no structure designed to stop the tooth at the crest. When the tow bar is being used, the inner member's movement within the confines of the outer member exposes the tow bar to damage and possibly to the detachment of a vehicle being towed from the towing vehicle.

[0014] The '042 reference also discloses an embodiment where the inner and outer members are secured by a pin attached on the outer member. The pin is adapted to insert through an opening defined by the inner member, thereby interlocking the inner and outer members. The problem with using a pin as a locking mechanism is that it might break, especially when towing a heavy load.

[0015] Another problem with the '042 reference is that high friction builds in between the pin and the opening or in between the latch and the dimple when a vehicle is being towed. Because of this high friction, a user may not be able to remove the pin from the hole or the latch from the dimple when the user wants to slide the inner member within the outer member to, for example, store the tow bar. This situation is commonly known in the art as being in a “bind.” To get out of the bind, the user would have to re-board the towing vehicle and drive the towing vehicle back and forth until the friction is relieved off the pin. Driving the towing vehicle back and forth may not even remove the bind, especially when the towing vehicle and the vehicle being towed are on an uphill surface.

[0016] Another tow bar is disclosed in U.S. Pat. No. 5,957,477 ('477 reference). The '477 reference has two leg members that are attached by a slideable collar, which moves between a locked and an unlocked position. Each leg member has an inner member that has grooves and an outer member that has catches. The catches attach to the grooves when the collar is in a locked position, thereby interlocking both members. Like the tow bar previously described, the catches might disengage from the grooves, especially when towing a heavy load.

[0017] The '477 reference is also susceptible to “binding.” In fact, the '477 reference provides a separate release tool for a user to remove an inner bar that is “bound” with the outer bar. Thus, a tow bar that has little or no tendency to “bind” is desired. Additionally, a tow bar that has an integrated tool for releasing “bound” members is also desired because separate tools are easy to lose and are complicated to use.

BRIEF SUMMARY OF THE ASPECTS OF THE INVENTION

[0018] The applicant has therefore provided an interlocking device. In the preferred embodiment, the interlocking device has an inner bar, which has a confined end disposed within the confines of an outer bar. A plug is attached to the confined end of the inner bar. The inner bar is slideable within the confines of an outer bar. The outer bar has a first end and a second end. A plug barrier is attached to the second end. When the inner bar slides towards the second end of the outer bar, the plug is adapted to abut the plug barrier thereby preventing the inner bar from sliding towards the second end.

[0019] The interlocking device further has an interlocking member attached to the plug by a bolt. When the plug abuts the plug barrier, at least a portion of the interlocking member moves transverse from the sliding axis of the inner bar. The interlocking member inserts through an interlocking member passage, which is preferably defined by the top wall of the outer bar. The interlocking locking member further abuts an interlocking member stop, which is also preferably defined by the top wall of the outer bar. The inner bar is stopped from sliding towards the first end of the outer bar by the interlocking member and the interlocking member stop, and the inner bar is also stopped from sliding towards the second end of the outer bar by the plug and the plug barrier.

[0020] The interlocking device preferably has a cam attached to the outer bar and adjacent to the interlocking member stop. The cam may be actuated to release the interlocking member from the interlocking member stop thereby allowing the inner bar to slide through the confines of the outer bar.

[0021] Additional features of certain embodiments of the invention will further be described below. It is to be understood that the invention is not limited in its application to the details of the construction and to the arrangement of the components set forth in the following description or as illustrated in the drawings. The invention is capable of other embodiments and of being practiced and carried out in various ways. Finally, it is understood that the scope of the present invention is to be determined by reference to the issued claims and not by whether a given embodiment meets every aspect of this brief summary or satisfies every deficiency or problem with the prior art as noted above.

BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Certain embodiments of the invention are shown in the following drawings where:

[0023]FIG. 1 is substantially a perspective view of an embodiment of the interlocking device.

[0024]FIG. 2 is substantially a longitudinal cross-sectional view of an embodiment of the interlocking device wherein the inner bar is in a locked position within the outer bar.

[0025]FIG. 3A is substantially a longitudinal cross-sectional view of an embodiment of the interlocking device wherein the inner bar is in an unlocked position within the outer bar.

[0026]FIG. 3B is substantially an alternate view of the embodiment depicted in FIG. 3A.

[0027]FIG. 4 is substantially a cross-sectional view taken from line 4-4 shown in FIG. 3A.

[0028]FIG. 5 is substantially a cross-sectional view taken from line 5-5 shown in FIG. 2.

[0029]FIG. 6 shows an embodiment of the interlocking device being used as tow bar legs for a tow bar system.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0030] In the following detailed description of the preferred embodiments, reference is made to the accompanying drawings, which form a part of this application. The drawings show, by way of illustration, specific embodiments in which the invention may be practiced. It is to be understood that other embodiments may be utilized and structural changes may be made without departing from the scope of the present invention.

[0031] Referring now to FIG. 1, the preferred embodiment of an interlocking device 20 is shown. Interlocking device 20 has an outer bar 24 and an inner bar 22. Outer bar 24 is preferably formed from a plurality of interconnected walls (only 32 and 34 are shown). The plurality of interconnected walls preferably define a rectangle-shaped outer bar and a square-shaped cross-section. The interconnected walls define a cavity within the outer bar, which is referred to as the confines of the outer bar. Alternatively, outer bar 24 may be formed from a hollow cylindrical tube.

[0032] Outer bar 24 has a first end 26 and a second end 27. Second end 27 is also referred to as the receiving end. Outer bar 24 preferably has a collar 28 attached to receiving end 27. Collar 28 is preferably cylindrical in shape. Collar 28 defines an inner bar passage 29. In an embodiment without a collar, inner bar passage 29 may be defined by the plurality of interconnected walls at receiving end 27.

[0033] Inner bar 22 enters the confines of the outer bar 24 through inner bar passage 29 and is slidable within the confines of outer bar 24. Inner bar movement from receiving end 27 and first end 26 defines a sliding axis. Inner bar 22 is preferably in a sliding fit relative to inner bar passage 29. The term sliding fit is used to refer to a configuration between members wherein a moving member has little or no room to deviate from the axis of movement. Thus, inner bar 22 preferably has little or no room to deviate from its sliding axis. The sliding fit configuration minimizes the generation of friction in the moving member, which may result in the moving member being difficult or impossible to move, or place the moving member in a “bind.” Inner bar 22 is preferably cylindrical in shape, but may be rectangular, triangular, or other shapes known in the art. Inner bar 22 is preferably made of steel, but may also be made of plastic, polymer, wood, or other materials known in the art.

[0034] With continued reference to FIG. 1, outer bar 24 has a cam mount 30 attached to one of the interconnected walls, preferably top wall 32. Cam mount 30 may be attached in between receiving end 27 and first end 26, preferably adjacent to receiving end 27. Cam mount 30 has a base 36 and a bolt holder 38. Bolt holder 38 preferably has two humps 37 positioned side-by-side. A channel 39 is formed in between humps 37. Humps 37 are adapted to attach a bolt 40 in between channel 39. Bolt 40 is adapted to rotatably attach a cam 42. Cam 42 rotates within cam opening (not shown) defined by base 36 of cam mount 30. Cam 42 preferably has an elongated handle 44. Elongated handle 44 may be attached to cam 42 or may be built unitarily with cam 42. Elongated handle 44 is preferably movable from 0 degrees to 180 degrees and within a rotational plane to actuate cam 42.

[0035] Outer bar 24 and collar 28 are preferably made of steel, but may also be made of plastic, polymers, wood, or other materials known in the art. Outer bar 24 and collar 28 may have different shapes, such as cylindrical, triangular, or other shapes known in the art. Outer bar 24 and collar 28 may be attached together preferably by welding, or by using adhesives or fasteners known in the art. Outer bar 24 and collar 28 may also be built unitarily, such as by molding.

[0036] Referring now to FIG. 2, inner bar 22 has a first end 62 and a second end 64. Second end 64 is preferably disposed inside the confines of outer bar 24. Second end 64 is also referred to as the confined end. A plug 66 is attached to confined end 64 of inner bar 22. A plug barrier 67 adapted to abut plug 66 is attached to outer bar 24 adjacent to or at receiving end 27. In the preferred embodiment, plug barrier 67 may be a bushing attached to outer bar 24. Bushing may define an opening (not shown in FIG. 2) continuous with inner bar passage 29. The diameter of the opening may be smaller than the plug diameter so that plug 66 can abut the bushing. In an alternative embodiment, plug barrier 67 may be collar 28 having a diameter smaller than the diameter of plug 66 so that plug 66 can abut collar 28. In yet another embodiment, plug barrier 67 may be receiving end 27 that defined inner bar passage 29. Receiving end 27 may have defined inner bar passage 29 with a diameter smaller than plug 66 so that plug 66 can abut inner bar passage 29.

[0037] When inner bar 22 slides in the direction towards receiving end 27, plug 66 eventually abuts a plug barrier 67. Plug 66 and plug barrier 67 therefore stop inner bar 22 from further sliding towards receiving end 27 and from detaching from outer bar 24. In the preferred embodiment, plug barrier 67 is preferably made of steel, but may be made of other materials known in the art, such as plastic, rubber, polymer, wood, and the like. Plug 66 is preferably shaped like inner bar 22, but has a larger diameter than inner bar 22. Of course, plug 66 may be of various shapes. Plug 66 is preferably in a sliding fit relative to outer bar 24. Inner bar 22 is also preferably in a sliding fit relative to plug barrier 67.

[0038] In the preferred embodiment, a bolt 70 attaches a block 72 to plug 66. Bolt 70 may also attach block to confined end 64 of inner bar 22. Bolt 70 is preferably disposed parallel to the sliding axis of the inner bar and substantially in between top wall 32 and bottom wall of outer bar 24 so that bolt 70 slides with inner bar in the sliding axis. Block 72 preferably extends over bolt 70, and portion of block 72 preferably defines a dome surrounding a portion of bolt 70. Cross-section of block 72 preferably tapers from bottom to top, so as to form a wedge-shaped structure.

[0039] Block 72 is movable from a first position where block 72 is substantially parallel to the sliding axis of inner bar 22 to a second position where block 72 moves transverse from the sliding axis of inner bar 22. In the preferred embodiment, a biasing device 74, such as a spring, is placed around bolt 70. When block 72 is moved to the second position, biasing device 74 moves block 72 transverse from the sliding axis of inner bar 22, and preferably the edge of the wedge goes into block passage 76. Block passage 76 may be an opening defined by top wall 32. Top wall 32 preferably define block stop 78. Block stop 78 may also be defined by cam mount base 36. Block stop 78 abuts the edge of the wedge. Thus, block 72 and block stop 78 prevent inner bar 22 from further sliding in the direction towards first end 26 of outer bar 24.

[0040] It can thus be seen from FIG. 2 that a positive mechanical interlock locks inner bar 22 within the confines of outer bar 24. Inner bar 22 cannot slide further in the direction towards second end 27 of outer bar. Inner bar 22 also cannot slide in the direction towards first end 26 of outer bar. Thus, it can be seen that, unlike friction-based locks disclosed in prior art, virtually no amount of force or pressure applied in the direction of the sliding axis of inner bar 22 can cause inner bar 22 to slide, unless components interlocking inner bar 22 with outer bar 24 are destroyed.

[0041] Referring now to FIG. 3A, cam mount 30 and cam 42 are preferably positioned adjacent to block passage 76. Cam 42 may be actuated by rotating cam handle 42 within its rotational axis. Cam 42 pushes block 72 against biasing pressure of biasing device 74 until block 72 is released from block passage 76 and block stop 78. Once block 72 is released, inner bar 22 may slide in the direction towards first end 26 of outer bar 24. A close up view of the cam is area is shown in FIG. 3B.

[0042] It is noted that the portion of block 72, which does not insert through block passage 76, is preferably sized to provide a sliding fit between said portion and the outer bar. Thus, block 72 has protrusion 83 reflecting the change in the block size from the portion of the block that inserts through the block passage to the portion of the block that is preferably sized to provide the sliding fit. As discussed above, the sliding fit feature helps prevent inner bar 22 from deviating from its sliding axis.

[0043] Referring now to FIG. 4, a cross-sectional view of interlocking device 20 is shown wherein inner bar 22 (shown in FIGS. 1-3) is locked from sliding within the confines of the outer bar. Block 76 (shown in FIGS. 1-3) has moved to the second position where it is transverse from the sliding axis of inner bar 22. Biasing device 74 is further shown to be parallel with the sliding axis of inner bar 22 so that biasing device 74 is adapted to move with inner bar 22.

[0044] Referring now to FIG. 5, a cross-sectional view of interlocking device 20 is shown wherein cam 42 is actuated to release block 72 from block stop 78. When cam 42 is actuated, cam 42 rotates with cam opening 45. A portion of cam 42 further extends through cam mount 30, block passage 76, and the confines of outer bar 24, thereby pushing block 72 against biasing device 74 to release block 72 from block stop 78. Once block 72 is released from block stop 78, inner bar 22 may slide in the direction towards first end 26 of outer bar 24.

[0045] It can thus be seen from FIGS. 2, 4, and 5 that while interlocking device 20 provides a positive mechanical interlock between inner bar 22 and outer bar 24, interlocking device 20 also allows a user to conveniently unlock the positive mechanical interlock by simply rotating cam handle 44.

[0046] Referring now to FIG. 6, the preferred environment of use for interlocking device 20 is shown wherein interlocking device 20 is used for a tow bar system. A tow bar system may have one tow bar leg or a plurality of tow bar legs. In the most preferred embodiment, interlocking device 20 is used as tow bar legs for a tow bar system having two tow bar legs. Each tow bar leg has an outer bar end 93 and 95 and an inner bar end 97 and 99. Outer bar ends 93 and 95 attach to a leg coupler 92 in substantially a y-shaped configuration. Leg coupler 92 attaches to a connecting bar 98, which attaches to a towing carrier 100. Inner bar ends 97 and 99 attach to a base assembly 102. Base assembly 102 attach to a carrier being towed 104. Base assembly 102, leg coupler 92, and connector 98 are well known in the art.

[0047] It can thus be seen that when certain embodiments of interlocking device 20 are used as a tow bar leg, interlocking device 20 provides a tow bar leg that has an inner bar mechanically interlocked with an outer bar. This positive mechanical interlock minimizes the risk of the inner bar detaching from the outer bar as the inner bar is stopped from sliding at one end by the plug and the plug barrier and from sliding at the other end by the block and the block stop. Thus, the positive mechanical interlock minimizes the chances for a vehicle being towed to separate from the towing vehicle.

[0048] Additionally, the sliding fit feature of some of the components of interlocking device 20 help prevent the inner bar from being misaligned within the confines of the outer bar. This feature allows interlocking device 20 to avoid the instance where, especially during disassembly and storage of the tow bar, the inner bar becomes difficult or impossible to slide within the outer bar because of friction. Interlocking device 20 further allows a user to conveniently unlock the inner bar interlocked with the outer bar by simply actuating a cam. This feature is especially helpful in contracting the size of the tow bar for storage.

[0049] Besides being used as tow bar legs, it should be appreciated that interlocking device 20 may also be used for devices using inner and outer members. Additionally, interlocking device 20 may be used for devices wherein the ability to adjust the devices' dimensions is a desired feature. As examples, interlocking device 20 may be used for construction devices that extend to a certain height to transport and allow a person to work on an elevated area, such as billboards. Interlocking device 20 may also be used for camera tripods, surveying equipment, cleaning equipment, and agricultural tools. Interlocking device 20 may further be used for support devices that have adjustable legs. When interlocking device 20 is used in the above applications, interlocking device 20 offers a sturdy positive mechanical interlock between members, a “bindless” inner and outer bar, and a convenient locking mechanism.

CONCLUSION

[0050] Although the description above contains many specifications, these should not be construed as limiting the scope of the invention but as merely providing illustrations of some of presently preferred embodiments of this invention. Thus, the scope of the invention should be determined by the issued claims and their legal equivalents rather than by the examples given. 

What is claimed is:
 1. A locking mechanism for securing an inner bar relative to an outer bar comprising: (A) an outer bar, the outer bar defining a cavity; (B) an inner bar at least partially moveable along an axis within the cavity defined by the outer bar; (C) a block operatively coupled to the inner bar, the block moving with the inner bar along the axis; (D) a block passage formed within the outer bar, wherein at least a portion of the block may be received by the block passage thereby preventing the inner bar from moving relative to the outer bar.
 2. The locking mechanism of claim 1, further comprising a biasing device in communication with the block and urging the block into the block passage.
 3. The locking mechanism of claim 2, the biasing device comprising a spring.
 4. The locking mechanism of claim 1, further comprising a block stop to engage the block when the block is received by the block passage.
 5. The locking mechanism of claim 1, further comprising a releasing mechanism coupled to the outer bar, the releasing mechanism adapted to force the block out from the block passage and thereby allow movement of the inner bar.
 6. The locking mechanism of claim 5, the releasing mechanism comprising a cam having a handle.
 7. The locking mechanism of claim 1, the block having a protrusion adapted to create a secure sliding relationship between the inner bar and outer bar.
 8. The locking mechanism of claim 1 further comprising a plug associated with the inner bar, the plug adapted to prevent the inner bar from sliding out of an end of the outer bar.
 9. The locking mechanism of claim 1, the cavity having a width, further comprising a plug barrier having a width less than the width of the cavity and adapted to abut the plug.
 10. The locking mechanism of claim 9, the plug barrier comprising a collar.
 11. The locking mechanism of claim 9, the plug barrier defined by a plurality of walls of the outer bar.
 12. The locking mechanism of claim 1, wherein the inner bar is slideable relative to the outer bar and the axis comprises a sliding axis.
 13. The locking mechanism of claim 12, wherein the block moves transversely to the sliding axis to enter the block passage.
 14. A method of securing an inner bar against movement relative to an outer bar comprising: (A) moving an inner bar inside an outer bar towards an end of the outer bar along an axis; (B) moving a block along with the inner bar along the axis; (C) moving the block into a block passage formed in the outer bar; and (D) abutting at least a portion of the block against a block stop, thereby preventing further movement of the inner bar.
 15. The method of claim 14, the step of moving the block into a block passage formed in the outer bar comprising moving the block transversely to the axis.
 16. The method of claim 14, further comprising biasing the block for entry into the block passage.
 17. The method of claim 14, further comprising guiding the movement of the inner bar within the outer bar using a structure on the block.
 18. The method of claim 14, further comprising releasing the block from the block passage by applying force to the block.
 19. The method of claim 18 wherein the force is transverse to the axis.
 20. The method of claim 18, further comprising using a handle to rotate a cam, a portion of the cam abutting the block when the block is in the block passage.
 21. The method of claim 14, the outer bar having a first end and a second end, wherein the block's entry into the block passage prevents the inner bar from moving further towards the first end.
 22. The method of claim 21, further comprising preventing the inner bar from moving past a certain point towards the second end.
 23. The method of claim 22, the step of preventing the inner bar from moving past a certain point towards the second end comprising abutting a plug operatively associated with the inner bar with a plug barrier operatively associated with the outer bar.
 24. The method of claim 22, the step of preventing the inner bar from moving past a certain point towards the second end comprising abutting a plug operatively associated with the inner bar with a plug barrier comprising a collar operatively associated with the outer bar.
 25. A tow bar system comprising: (A) a leg coupler; and (B) at least one tow bar attached to the leg coupler, the tow bar comprising: (a) an outer bar, the outer bar having a first end and a second end and defining an inner bar passage and a block passage; (b) an inner bar, at least a portion of the inner bar being moveable along an axis and disposed within the confines of the outer bar; and (c) a block operatively associated with the inner bar and moveable with the inner bar along the axis, the block being transversely movable relative to the axis, the block being adapted to enter the block passage, thereby preventing the inner bar from sliding towards the first end of the at least one tow bar.
 26. The tow bar system of claim 25, further comprising a plug associated with, and moveable with, the inner bar, the plug being adapted to stop the inner bar from sliding towards the second end of the outer bar.
 27. The tow bar system of claim 26, further comprising a plug barrier associated with the outer bar, the inner bar being stopped from sliding towards the second end of the outer bar when the plug abuts the plug barrier.
 28. The tow bar system of claim 27, the plug barrier further comprising a collar attached to the second end of the outer bar.
 29. The tow bar system of claim 27, the plug barrier further comprising a bushing attached to the confines of the outer bar.
 30. The tow bar system of claim 25, further comprising a cam, the cam adapted to abut the block and move the block out of the block passage.
 31. The tow bar system of claim 25, further comprising a biasing device associated with the inner bar, the biasing device biasing the block towards the block passage.
 32. The tow bar system of claim 31, wherein the block is attached in between the biasing element and the inner bar, the biasing element being adapted to move the block transversely relative to a sliding axis of the inner bar.
 33. The tow bar system of claim 25, further comprising: (A) a connecting bar coupled to the leg coupler and adapted to be attached to a towing vehicle; and (B) a base assembly, at least one tow bar connected to the base assembly, the base assembly adapted to be attached to an object to be towed.
 34. A locking mechanism comprising: (A) an outer bar, the outer bar comprising a first end and a second end; (B) an inner bar, at least a portion of the inner bar being moveably disposed within the outer bar to move along an axis; (C) a first stopping means, moveably associated with the inner bar to move along the axis, for stopping the inner bar from moving towards the second end of the outer bar; and (D) a second stopping means for stopping the inner bar from moving towards the first end of the outer bar.
 35. The locking mechanism of claim 34, wherein the outer bar defines a passage into which the first stopping means extends when the inner bar is secured against moving towards the second end of the outer bar.
 36. The locking mechanism of claim 35, further comprising a biasing means for biasing the first stopping means into the passage.
 37. The locking mechanism of claim 35, wherein the first stopping means moves transversely to the axis when extending into the passage.
 38. The locking mechanism of claim 35, further comprising a releasing means for releasing the first stopping means from the passage.
 39. The locking mechanism of claim 34, further comprising guiding means for guiding the movement of the inner bar within the outer bar.
 40. The locking mechanism of claim 39, wherein the second stopping means comprises an abutting means adapted to abut a structure operatively associated with the outer bar, thereby preventing the inner bar from moving further towards the first end of the outer bar. 